


workin' on it, darling

by parsnipit



Series: flashpoint [2]
Category: Undertale (Video Game)
Genre: (not in the main relationship), Aftercare, Alternate Universe - Underfell (Undertale), Brief insecurities, Control and a Lack Thereof, Cuddling & Snuggling, Fellby's Libido, Implied Sexual Content, Implied/Referenced Rape/Non-con, M/M, Not Suitable/Safe For Work, Possessive Behavior, Power Dynamics, Power Play, Unhealthy Relationships, not explicit but definitely, unhealthy but surprisingly functional!
Language: English
Status: Completed
Published: 2019-12-18
Updated: 2019-12-18
Packaged: 2021-02-25 20:53:59
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,073
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21851758
Author URL: https://archiveofourown.org/users/parsnipit/pseuds/parsnipit
Summary: Gaster is a small god. Grillby had known that the moment he’d waltzed into the nightclub for the first time—he carried himself with the quiet confidence that so few monsters have. He walks with the manner of a monster who knows he’s going to get where he wants to be and need not do anything else to ensure he gets there. If someone gets in his way, he has only to give them a sharp word or a sour look to send them scurrying. If he’s in a particularly crass mood, he might resort to shoving, but Grillby is under no delusions that he needs to shove. If he wants his way through, he’ll have it, and he’ll have it with ease. Grillby's small god manages every inch of his universe with impeccable control.Gods,but it’s fun to shake that control up, sometimes.
Relationships: W. D. Gaster/Grillby
Series: flashpoint [2]
Series URL: https://archiveofourown.org/series/1574302
Comments: 3
Kudos: 70





	workin' on it, darling

**Author's Note:**

> warnings: a couple of brief references to rape-y things, references to violence, some nsfw stuff (nothin explicit) because i can’t control fellby’s libido
> 
> written for a prompt from @anchestor on tumblr!

Gaster is a small god. Grillby had known that the moment he’d waltzed into the nightclub for the first time—he carried himself with the quiet confidence that so few monsters have. Oh, there are  _ bold  _ monsters at the club. There are monsters who claw their way to the top, who push and shout and shove, who swagger and strut. Their arrogance is a permanent part of the club’s atmosphere. There are cowards, too, monsters who slink and prowl and hunt from the outskirts. But Gaster—

Gaster is different. He always has been.

He walks with his head up, his shoulders straight, his steps measured and focused. He doesn’t strut, and he doesn’t slink. He just...walks. He walks with the manner of a monster who knows he’s going to get where he wants to be and need not do anything else to ensure he gets there. If someone gets in his way, he has only to give them a sharp word or a sour look to send them scurrying. If he’s in a particularly crass mood, he might resort to shoving, but Grillby is under no delusions that he  _ needs  _ to shove. If he wants his way through, he’ll have it, and he’ll have it with ease.

He is a small god, and he manages every inch of his universe with impeccable control.

_ Gods,  _ but it’s fun to shake that control up, sometimes.

Gaster had invited him over for dinner. In itself, this is not an unusual occurrence—they eat dinner together at least once a week, typically. Grillby always shows up early, because if he doesn’t, he knows they’ll be eating lukewarm, stringy ramen and black coffee. He’ll cook, and Gaster will laze around the kitchen and watch him with the smug expression of a cat in a particularly sunny spot. Safe, secure, in control.

Not for long.

“So,” he says, leaning back against the counter and making a point of elbowing Gaster’s sugar jar out of its place against the war, “big plans for the night?”

“Mm, I was hoping we could fuck.” Gaster eyes the displaced sugar jar unhappily. “Other than that, no.”

Grillby sighs wistfully. “Man, you really are a romantic.”

“Sorry, did you want to be wooed first?”

“Well, it wouldn’t kill you to put a little effort in.” He drapes his wooden spoon over his shoulder, allowing it to splatter sauce across Gaster’s perfectly polished counter. Gaster’s eye socket twitches.  _ Stars,  _ but he’s easy to rattle. He has exactly  _ zero  _ self-control—he claws what control he does have from his environment, from micromanaging the world around him to the point of obsession, and as soon as that perfect little world is disturbed—

Well, then things gets  _ fun. _

(Besides, it’s...nice, to see Gaster lose control for a little while. It’s nice to be reminded that he’s just a monster, and not really some great, omniscient creature. It’s nice to see him relax and  _ trust  _ for half a fucking second.)

“Alright, alright,” Gaster says, leaning back in his chair. “What do you want? Flowers? A song? Sweet nothings whispered in your ear? A portal to a previously unknown dimension capable of wreaking havoc on society as we know it? Name it, it’s yours, you spoiled brat.”

Grillby licks sauce off of his spoon, then drops it back into the pot with a clatter. “I wanna try a new recipe.”

Gaster flings his hands in the air, although there’s a distinctly  _ ruffled  _ air about him as he does. Grillby grins. “Have at it.”

Grillby has at it. See, the thing is, Gaster has a distaste for anything new or unplanned. Some of it stems from his pride, and a good portion of it from his distrust of everyone and everything—but part of it is genuine distress at the idea of change, and Grillby does loathe to cause his boyfriend any unhappiness. Sure, the fucker’s fun to rile, fun to kick out of his comfort zone every once in a while, but Grillby  _ does  _ care about him. He’s a soft spot in the elemental’s nature, and one Grillby doesn’t mind so much. (Actually rather enjoys, if he’s being honest.) So it is that they have this little ritual: if Grillby wants to shake things up, he’ll push and push and  _ push. _ If Gaster starts to get genuinely upset, he’ll say  _ stop.  _

Easy enough, right? Easy enough that Grillby doesn’t feel uncomfortable tossing Gaster another few curveballs tonight, at the very least—so far, Gaster’s handling it rather well. Perhaps he’s getting used to these games Grillby plays. (Perhaps he’s beginning to realize that being out of control around Grillby is safe and okay and maybe even a little bit  _ fun.) _

A brief half-hour later, Grillby serves tortellini with spinach and sausage and a dash of habanero, just to  _ heat  _ things up. Gaster hisses as he tastes the spice, his eyes watering, and Grillby cackles. “What, really? It’s not _ that _ spicy, you wuss.”

“Fuck you,” Gaster says, jamming another spoonful into his mouth and glowering at Grillby through watery eyes. “You’re the worst.”

“You love me.” Grillby leans forward, dropping a kiss against the tip of his nose.

“Gods, I don’t know why.”

“It’s the hot bod, isn’t it?”

“That’s lust, stupid.”

“My dashing charm? How suave I am? How drunk I get you? The money, the power, the confidence? And hey, I  _ am  _ a pretty great lay.”

Gaster twirls his fork thoughtfully in the air. “Mm, maybe. I don’t think that’s all, though. Keep going.”

“I don’t want to and you can’t make me.”

“You just ran out of nice things to say, didn’t you?”

Grillby shrugs, his eyes flicking away. Damn, but Gaster is a perceptive little fuck, isn’t he? He’s far sharper than any one monster has a right to be.

“Mm, fortunately for you, I can think of more.” Gaster pushes his plate away, bracing his elbows on the table and propping his face in his hands. “Your general badassery, the whole brazen intimidation thing you’ve got going on, the way you control your bar and everyone in it, the pride you take in your work—”

“Stoooop,” Grillby complains, batting a hand over his mouth. Gaster, lo and behold, does not stop.

“—your patience when it comes to dealing with assholes like me, your enthusiasm for cooking, your steadfastness, your ambition, your dumbass courage, your forgiving nature—though perhaps that’s selfish of me—and your intelligence. And yeah, okay, you’re a pretty great lay. Credit where credit’s due. Now, if you’d like me to break it down further—”

“No thank you that’s completely alright,” Grillby says quickly, then lurches forward to kiss Gaster before he can ignore him and do whatever the fuck he pleases, as he is so foolishly fond of doing. Damn him, but he’s somehow managed to wrest control away from Grillby and into his own hands again. He’s terribly good at that. (He’s had a lot of experience prying control away from people.) Grillby kisses him  _ quite thoroughly  _ to make up for his momentary loss of control, and Gaster makes pleased little noises that tell Grillby he isn’t exactly feeling repentant. 

“So,” he purrs, once Grillby pulls back. “Are you done eating?”

“Nope.”

“You’re a bottomless pit.”

“Tell me about it,” Grillby says, shoveling another forkful of food into his mouth. “Have a little patience. Go pull the movie up.”

Gaster groans but drags himself off towards the living room. 

“Hey,” Grillby calls after him, “let’s watch  _ Home Alone.” _

“What? That’s not what we decided yesterday. And why the fuck would we watch that?”

“Um, because it’s  _ peak humor,  _ and it’s almost  _ Gyftmas.” _

“That’s your idea of peak humor?” Gaster pinches the bridge of his nose, closing his eyes. This wasn’t in his plan, either—just how Grillby likes it. “You’re infantile.”

“I wanna watch it, Dings. Dings. Dings. Diiiiings, I’ll make you cookiiiiies—”

“Alright, alright! Gods, fine. You and your bribery.”

Grillby wolfs down the rest of his food—and just in time, too. Gaster clearly hadn’t planned on pausing the movie for him, the little brat. Grillby flops over the back of the couch and into Gaster’s lap, and Gaster sighs and pats his face. “Stupid,” he says, but his voice is quiet and just a little bit fond and Grillby burns warmer. 

They snuggle up on the couch, and they watch their silly little movie, and Grillby chuckles at all the shittiest jokes just to see Gaster roll his eyes and sigh and try to hide the smile that threatens to flicker across his face. As they watch, Gaster gradually begins to relax beneath his weight, one hand moving absently to pet over his chest and shoulders. Grillby stretches into the pets like the oversized mutt he is, and Gaster grumbles but slips the hand beneath his shirt to scratch across his stomach. Grillby sighs in pure contentment. Oh, life is  _ good.  _

When the credits begin to roll, Gaster leans down, bonking their foreheads together. “Okay,” he admits. “That was pretty good.”

Grillby grins. “Glad you thought so. Not so bad, letting me decide stuff every once in a while, is it?”

Gaster makes a noncommittal sound, beginning to draw back, but Grillby reaches up and cups a hand gently behind his skull before he gets too far. “What?” Gaster asks, blinking at him. “What is it?”

“C’mere.”

“Why?”

“I want to kiss you, silly.”

“Well, I can’t say no to that.” Gaster leans back towards him, and Grillby tips his chin up and fits their mouths together with a pleased crackle. This kiss he keeps soft, gentle—a quiet comfort and consolation for the bruising kisses he plans to give soon. He draws back after a moment, and Grillby slides his palm down to cup Gaster’s cheek. Gaster leans into him, eyes closing for the briefest of moments, and even that tiny display of trust has Grillby sparking with pride.

“I love you,” he tells Gaster, and he does. Gaster is one of only two monsters he loves, in this whole goddamned world—and he plans to keep it that way. Loving too many people is a liability. (Loving any one person is a liability, and Grillby panics if he thinks about it for too long.)

“I know.” Gaster reaches down, cradles the side of Grillby’s throat. He threads his fingers through the thin golden chain there, humming quietly. “Poor thing.”

Grillby frowns, pushing himself up and onto his knees. He reaches out, takes Gaster’s hips, and yanks the lanky skeleton beneath him. Gaster yelps, but he doesn’t try to squirm away, so Grillby does what he does best—he pushes. He drops his hands to the couch on either side of Gaster’s head, scowling at him. “Poor thing? Hardly. I’m lucky to have you.”

Gaster opens his mouth to argue, then falters. “...alright,” he amends, after a moment. “Alright, fine.”

“Hell yeah you are,” Grillby agrees enthusiastically, leaning down to mouth at Gaster’s jaw. “One fine gentleman I’ve got right here, boys. Smartest monster in the Underground—I mean, you can’t get finer than that.”

“Alright, suck-up, that’s enough.” Gaster bumps their heads together playfully, twisting so he can nip Grillby’s cheek.

“Mm, if you’re good, I could be convinced to suck something else,” Grillby says, nuzzling into the crook of Gaster’s neck. Gaster wraps his arms around Grillby’s shoulders, humming thoughtfully.

“Tempting, tempting,” he admits, his fingers curling idly through Grillby’s flames. “And what does being good consist of tonight?”

“I want to decide what happens.” Grillby keeps himself close to Gaster—something warm and steady for Gaster to latch on, if his fears rear their ugly heads. And, almost immediately, Gaster begins to still beneath him, fingers gripping his shoulders more tightly.“I want you to do what I tell you. I want you to trust me to take care of everything, to make you feel good, to keep you safe. Can you manage that?”

It isn’t a trick question—sometimes Gaster can manage it, and sometimes he can’t. It depends on a host of factors, and Grillby isn’t about to force Gaster into something he’s uncomfortable with. Grillby’s a sleaze and a whore, not a fucking  _ rapist.  _ He waits patiently, unmoving, as Gaster decides.

“I—maybe,” Gaster says, after a moment. “Maybe.”

“You know what to do if you need me to stop.”

“I know.” Gaster squeezes him close in a clumsy hug, and Grillby crackles soothingly at him. “I trust you.”

Stars, Grillby could burn down worlds for those words alone. He kisses Gaster again, bearing into him with an excited growl, popping flames and hissing smoke and sparking in ways that leave Gaster shivering with delight. With one hand, he gathers Gaster’s wrists and pins them gently above his head. The other hand plays across Gaster’s bones, doing its damned best to wrest gasps and whines and shudders out of him. (And, Grillby is pleased to say, its damned best is  _ pretty damned good.) _

“Fuck, Grillby—” Gaster hisses between his teeth, pulling a leg up and bracing his knee against Grillby’s crotch. Mmm—Grillby rocks his hips gently against it, curling himself down and bracing a forearm beside Gaster’s head. 

“Workin’ on it, darling.” He squeezes Gaster’s wrists gently, pressing them against the armrest. “Keep those there.”

“Bossy, bossy.”

Grillby sinks his teeth into the vertebrae of Gaster’s neck, and Gaster gasps and growls but, when Grillby moves his hand, keeps his wrists where Grillby told him to. He smooths his palm across Gaster’s side, hooks his fingers beneath the hem of Gaster’s shirt, and hauls it up and over his head. Then he leans down, scraping his teeth across Gaster’s sternum and curling his fingers through his ribs. Gaster’s soul gleams out at him, bright and fierce, and  _ oh,  _ how Grillby is tempted to touch it—

But that is one line Gaster has refused to entertain crossing, and Grillby crosses no line without his lover’s consent. (He knows well what it feels like to be on the other end of  _ that,  _ and he wouldn’t wish it on an enemy, let alone  _ Gaster.) _

Gaster’s soul may not be his yet, but stars, Grillby  _ owns  _ his body. And, as he does with anything he owns, he takes immaculate pride in it—he’s memorized every one of Gaster’s sweet spots, every touch that makes him gasp and writhe and choke on moans. He puts this knowledge to most  _ dastardly  _ use, and although Gaster makes a good effort, his lack of self-control is quick to rear its head again. He pulls his arms down, curling them around Grillby’s neck and pulling him into another bruising kiss. Unfortunately, whilst Grillby is very much not opposed to this, there are expectations to be upheld. 

“Ah, ah, ah,” he chastises, pulling back and reaching for Gaster’s wrists again. “Watch yourself, Dings.”

Gaster groans in frustration, but he doesn’t fight Grillby’s grip on him, so Grillby pins his hands above his head again. “I want to  _ touch,”  _ he whines. “You’re so meeeean.”

“Mean?” Grillby grins at him, nipping beneath his jaw. “Oh, little devil, I can  _ show  _ you mean, if that’s what you want.”

Gaster gulps.

“Heh. Maybe not tonight, huh?” Grillby kisses along his vertebrae, his clavicle, but he can’t go any farther—not while he’s busy trapping Gaster. “We’ll save it for next time. I’ll plan us something  _ special.” _

He reaches back with his free hand, pushing Gaster’s leg out of the way before placing his own leg atop Gaster’s pelvis and grinding down. Gaster’s back arches, and he bites back on the choked cry that threatens to leave him—they can’t be having  _ that.  _ If Gaster’s able to control himself that much, Grillby must not be working hard enough. After all, this is all about wresting Gaster’s control away from him and making it feel _ good. _

So Grillby buckles down, and he damn well gets to work.

When they finish, they both lay panting on the couch, and Grillby feels flush with heat and satisfaction and an inordinate amount of affection for the skeleton beneath him. He mouths lazily at Gaster’s neck, a nonverbal mantra of  _ mine mine mine mine,  _ and Gaster clings and shivers and basks in the attention. “Good,” Grillby mumbles against his vertebrae, beyond pleased, “good job, Dings. Incredible. Feel good? Feel okay?”

“‘Okay’ would certainly be an understatement,” Gaster says breathlessly, his hands roaming across Grillby’s back and shoulders, curling into the hard-packed embers of his core. “Gods, sometimes I forget how wonderful you are.”

Grillby hides his smile against Gaster’s shoulder, although he can’t quite stop the pleased green sparks that lash through his flames. They lay there for quite sometime, because Gaster gets  _ clingy  _ after Grillby drags him out his comfort zone. Clinginess has never been something he liked, before, but with Gaster—with Gaster, it sends a pleased little thrill through him. Gaster  _ needs  _ him. Grillby is more than happy to indulge that need; he snuggles against the skeleton, murmurs soft teases and gentle comforts, tries to remind him that they’re safe and nothing bad is going to happen as long as Grillby’s here, because Grillby’s got him, Grillby’s safe, Grillby’s worth his time and his trust.

For a brief moment, Grillby even dares to hope that Gaster believes him.

Then they get up, and Grillby tugs his pants back on, and he goes to work restoring Gaster’s control. He pushes the sugar jar back into its rightful place. He wipes sauce from the counter and turns on the movie they’d initially planned to watch. He makes chocolate cookies, as he’d promised Gaster in return for  _ Home Alone.  _ Gaster watches everything with the unguarded affection he gets, on nights like these, and says, “If anyone hurt you, I would vivisect them for nine years.”

Grillby rests a hand over his soul, touched. “Aw, babe.”

They stay together the rest of the night, curled around each other in their sleep. When Grillby snaps awake, sparking and startled by the plague of his nightmares, Gaster is there to reason his fears away and lull him back to sleep with lazy kisses and lazier touches. He doesn’t wake again until dawn, when the artificial lights outside flicker on. When he leaves Gaster that morning, he is secure in the knowledge that his little god is safely in control of the universe again—leastways, until the next time Grillby comes to visit.


End file.
